Tail gate elevator



May 15, 1951 W. M. WOODWARD 2,553,156

TAIL GATE ELEVATOR Filed Oct. l5, 1948 2 SheeS-SheeiI l May 15, 1951 W, M. wooDwARD TAIL GATE ELEVATOR 2 Sheets-SheefI 2 F'i'led Oct. 13, 1948 Patented May 15, 1951 UNITED PATENT OFFICE y255a15e 'rain GnTE ELEVATQR. Wilfred Wopdward, New Brunswick, N. J. Applicatie@ o'tqter '13, 194s, serial No. 54,299 s claim-s. (o1. zii-'75j Y My invention relates to a screw-propelled .tailgate elevator and more particularly/to an improvement in the construction and relationship of parts in such a device.

This application replaces and relates back for subject matter to my application Serial No. 645,282 led February 4, 1946 andnow abandoned.

It is an object of the invention to .provide a screw-propelled tail-gate elevator which has no part projecting to the ground when the gateis elevated to its position at the truck platform.

It is another object of the invention to provide a screw-propelled .tail-gate elevatorin which the screw drive is located adjacent .the truck platform and -in which the load is not transmitted through the drive mechanism.

Another object of the invention is to provide a screw-propelled tail-gate elevator which may be of relatively light weight and yetY handleheavy leads without binding or iiexure ofthe screws.

These and other objects of the invention and. the various features and .details yof the construction and operation thereof are hereinafter yfully set forth and described with reference .to the accompanying drawings, inwhich:

Fig. 1 is a view in perspective of the rear end of a truck embodying the present invention and showing the tail-gate in the elevatedand closed position;

Fig. 2 is an enlarged view similar to Fig. 1 showing the tail-gate in the elevated open position, the lowered position thereof being shown in dotted lines;

Fig. 3 is a perspective View of a tail-gate made accordingr to the 'present invention;

Fig. 4 is an enlarged sectional view taken on line 4 4, Fig. 3;

Fig. 5 is an enlarged sectional view taken on line 5 5, Fig. 4;

Fig. Bis an enlarged fragmentary sectional view through the drive mechanism forlowering and elevating metan-gate; and

Fig. 'l is a sectional view taken online 1 1, Fig. 6.

Referring now more particularlyto the drawings, reference numeral l designates ,atail-gate which is hinged as indicated at .2 to a crossmember 3. In accordance with thepresent invention, the tail-gate I is mounted for `ve'rtilz'al movement between the lowered and elevated A positions shown in Fig. 2 of the drawings. To thisv end, therefore, the cross-member 3 is rigidly connected at each end to a vertical t'zolumnr 4 adjacent the lower end thereof. The columns-4 are hollow, and preferably of Square or rectangular cross-section shape as indicated, and are mounted to 'slide telescopically within xedly mounted outer columns or posts 5 of a corre'- spondingly larger cross-sectional size and shape.

By making the telescoping pairs of columns 4 and posts 5 of square or rectangular cross-V sectional shape as shown and described; greater rigidity'and'strength are imparted .to the structure with the result that the loadcapacity of .the tail-gate is substantially increased. In addition, such square or rectangular structural shapes. are usually employed for the frame posts of .the bodies of vehicles and hence the outer posts 5 may constitute the customary rear frame posts kof the body Bof a truck. or vehicle l as shown in Figs. 1 and 2. Thus, the tail-gate of the present invention may be .manufactured .in .such man ner .that the @Qlumns 4 may Slide telSQQPiCelly within the .rear frame Yrests .0f existing trllek bedies .or .the bail-.sate .may be inCQrPrigd readily intoa truck orvehicle body in the co of its manufacture withcutl material dev" from .its originally designed construction.

The @Hier faeeef @aah Of' th ved Columns o r posts -il is providedwith a longitudinal fslti .3 whichv extends upwardly therein a predetermined distan from the bgttemedgefofth gil'mifri. and` provides anopening orltrack for the passage Oran'. outwardly .projecting 111g 9 .which S Ceef breach 60111111114- Pvoted tracs .l0 glas" bfe cgnnected between .Oppgsit .ends ofthe tail-.gate land themes@ t0 .suppotthegate in herientel positionand to permit it to be swung aboutthe hingel ,to a vertical .positive when setlists?. forexample. as Shown inFigS- 1 and 2 0f *11.1.6 drawings.

The lower end. 0f ,each 0f the GQ1141113S-I41SQ0 videdwith a. Cap or Closure l l which ,haSepQrtion l2 of reduced size arranged to fit intothe end of the .column and providing a-.perphglal shoulder vI3 upon which .the lower end .edges .of thfe columnare adapted toiseat;A for eXampleLas shown .in Fig. 4 of the drawings. ,.,Theilpper endof each of the columns ll'is provided with a Similar cap `or.closure i4 whichjlikewisehas an inserted'portioul of reduced size providing a peripheralshoulder l thatis adapted to engage or 'seat upon the upper end edges of vthe column.

.Extending longitudinally within each of the columns `4 is ath'readedbarll which has ,its opposite ends 'secured in the end caps. Si and I4, respectively, in a manner topre'vent rotation of thebars I1 with respect tothe columns. l'Ihus, the lower and upper ends of the bars Il may be provided with reduced portions i8 of square or.

3 rectangular cross-sectional shape which engage slidably within elongated rectangular slots I9 in the lower and upper caps or closures II and I4, respectively. The bars I1 are further provided with projecting threaded end portions 26 that receive nuts or the like 2l as more clearly shown in Fig. 5 of the drawings, the arrangement being such that when the nuts 2I are tightened upon the ends 2e of the bars Il, the nuts do not bind against the caps II and I4 to prevent movement of the ends of the bars i1 within thel slots I9. By this construction and arrangement it will be observed that the bars Il are effectively anchored against rotation and that they serve also as tie-rods to retain the caps II and I4 in and rmly against the opposite ends of the colv umns 4.

It is to be noted that the elongated slots I9 provided in the caps or closures II and I4 at the lower and upper ends of the columns 4 have their long axes extending in the fore and aft direction with respect to the truck or vehicle 'I in which the device is installed and, as previously stated, the reduced square or rectangular portions I8 ofthe bars I1 slidably engage within the slots I9 so that the ends of said bars may move in a fore and aft direction within the limits of the slots I9. The ends of the bars I'I are thus provided with a floating mounting which permits movement of the columns 4 and end closures I I and i4 relative to the bars I'I, thus preventing bending of the bars I'I and consequent binding thereof in the threaded sleeve 28. This structure is advantageous for the easy operation of very light apparatus when excessive loads are imposed on the tail gate I. A heavy load tends to flex the columns 4, and if these columns are light, and if a rigid connection existed between these columns and the bars Il, the latter would also tend to flex and cause the undesired binding action referred to above in which case it would be very diicult, if not impossible, to properly operate the mechanism.

A Fixedly secured to the inner face of each outer column 5 at the 1ower end thereof and beneath the oor 22 of the vehicle body 6, is a bracket 23 having arm portions 24 that extend through suitable openings 25 in the columns 5 and inwardly of the telescoping columns 4 through elongated slots 26 which extend longitudinally in each co1- umn 4 from a point adjacent the lower end thereof to a predetermined point adjacent the upper end of the column. The inwardly extending arm portions 24 of the brackets 23 terminate in collar portions 2l which surround the threaded bars I1 in spaced relation axially thereof as shown in Fig. 6 of the drawings.

Threaded on each bar I'I intermediate the collar portions 2'I is a sleeve 28 which has its opposite ends journaled in said collar portions 21 by means of bearings 23, and secured upon or formed integral with each sleeve 28 intermediate its ends is a spiral gear 3D. Each of the spiral gears 30 meshes with a similar spiral gear 3| that is xed upon a shaft section 32 which is journaled in spaced aligned sleeve portions 33 of the brackets 23, and thrust bearings 34 are interposed between said sleeve portions 33 at opposite sides of the gears 3|. One of the shaft sections 32 and its associated spiral gear 3I is adapted to be rotationally driven by means of a hand crank 35, and driving connection from said one shaft 32 to the other may be established through an intermediate shaft 36 connected therebetween, for example, by means of universal joint connections 31, as shown in the drawings.

From the foregoing description it will be observed that with the tail-gate I in the position shown in Fig. 2 of the drawings, actuation of the crank 35 in a clockwise direction with respect to the drawings will cause the gears 3I to rotationally drive the gears 30 and sleeves 28 in counterclockwise direction with respect to Fig. '7 thereby causing the threaded bars Il to feed downwardly carrying with them the inner columns 4, crossmember 3 and tail-gate I to the dotted line position shown in Fig. 2. On the other hand, actuation of the crank 35 in clockwise direction operates to drive the sleeves 28 in the reverse direction of rotation thereby causing the bars I'I to feed upwardly through the sleeves and, of course, causing the columns 4 to telescope within the columns 5 Vthereby elevating or raising the tail-gate I from the dotted line position of Fig. 2 to the solid line position therein.

From the foregoing description it will be observed that the present invention provides a tail gate having novel and improved mechanism for lowering and raising the tail gate and embodying features of construction operable to prevent binding of the lift mechanism as a result of stresses and strains imposed thereon by bending moments produced when loads of great weight are raised or lowered upon the tail gate. The invention also provides a tail gate construction of the character set forth which may be readily and easily incorporated in and as a part of the body structure of a vehicle in the course of manufacture thereof or subsequently. The invention furthermore provides a device of the character described which is of relatively simplified and economical construction and which may be readily manufactured, assembled and installed.

While a particular embodiment of the present invention has been illustrated and described herein, it is not intended to limit the invention to such disclosures and modifications may be made therein and thereto within the scope of the claims.

I claim:

1. The combination with a vehicle body of a tail-gate elevator comprising a pair of xed vertical posts, a pair of columns slidably journaled in said posts for movement up and down, a tailgate hinged to the lower ends of said columns for movement between vertical and horizontal positions, a pair of fixed bracket members, an internally threaded sleeve journaled in each of said bracket members in a manner to take vertical thrust, driving mechanism connected to rotate said sleeves, a pair of screw bars each secured at its ends to the top and bottom of one of said columns and threaded in one of said sleeves, said fixed brackets and the lower ends of said xed posts being located adjacent the floor of said vehicle body.

2. The combination as set forth in claim l in which said posts are hollow, and said columns are telescoped inside said posts, the columns being slotted to pass said bracket members.

3. The combination as set forth in claim l in which said posts are hollow, and said columns are telescoped in said posts, the columns being slotted to pass said bracket members, and said tail-gate is provided with folding braces to strengthen the tail-gate in horizontal position, said posts being slotted to pass said braces.

4. The combination as set forth in claim l in which the ends of said screw bars are secured to said columns in a manner to permit limited horizontal movement of the bar within the column U whereby a load tending to iiex a column does not flex its screw bar.

5. A tail-gate elevator comprising a pair of xed vertical posts, columns slidably journaled in said posts for vertical movement, a cross member secured between the lower ends of said columns, a tail-gate hinged to said cross member for pivotal movement between vertical and horizontal positions, collapsible braces pivotally connected between said columns and the outer ends of said tail-gate to support the same in horizontal position, vertical slots in said posts for reception of a portion of said braces, bracket members fixed on said posts and projecting inwardly of said posts and said columns, internally threaded sleeves journaled on said members, a gear on each of said sleeves, driving gears rotatably mounted in said brackets and meshing with said rst named gears, top and bottom closures on said columns, said closures each having a slot therein extending in a direction normal to the hinge axis of said tail-gate, screw bars threaded in said sleeves, the end portion of said bars being slidably received in said slots whereby upon flexure of said columns under the action of a load on said tail gate bending of said bars and consequent binding thereof in said sleeves is prevented, said bars being fixed in said closures against rotation and longitudinal movement relative thereto whereby upon rotation of said driving gears said sleeves will be rotated to move said bars and said tail-gate up or down.

6. A tail-gate elevator comprising a pair of fixed vertical posts, columns telescopically received within said posts for vertical movement relative thereto, a tail-gate hingedly connected to said columns for pivotal movement between vertical and horizontal positions, bracket means xed on said posts, internally threaded sleeves rotatably mounted on said bracket means, driving means for said sleeves, top and bottom closures on said columns, said closures each having a slot therein extending in a direction normal to the hinge axis of said tail-gate, threaded bars extending longitudinally within said columns, and threadedly engaging said sleeves, the end portions of said bars being sldably received in said slots, said bars being fixed in said closures against rotation and longitudinal movement relative thereto, whereby upon actuation of said driving means said sleeves will be rotated to move said bars and said tail-gate up or down and whereby any rlexure of said columns under the action of a load on said tail-gate will not be transmitted to said bars thus preventing binding of said bars in said sleeves.

WILFRED M. WOODWARD.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,280,090 Schrottky Sept. 24, 1918 1,526,621 Zaun Feb. 17, 1925 1,628,880 Heise May 17, 1927 2,200,436 Van Blarcom et al. May 14, 1940 2,236,317 Howland Mar. 25, 1941 2,405,054 Pringle July 30, 1946 

